Electret Recharging

In 1991, RTCA® introduced a technique to recharge spent electrets. All Electret users can take advantage of this process and have spent electrets recharged so they can be reused repeatedly for radon gas measurements.

The Electret system provides time-integrated radon values by measuring the change in an electret’s surface potential as a function of gas concentration. “Electrets can be used repeatedly as long as their surface potential is within the useful voltage range (200 to 800 V). When they fall below this range, they can be recharged and reused.”¹

Under carefully conducted testing conditions, RTCA® has found that electrets recharged by RTCA® maintained their surface potential for the same period as initially charged electrets. When electrets are submitted to RTCA® for recharging, the standard operating procedure is to subject the units to temperature and humidity stressing and monitor the voltage stability of the recharged electrets for a minimum of two weeks. RTCA® maintains a QA document for every recharged electret. RTCA® notes any stability problems and advises client of same. RTCA®’s ability to recharge an electret depends in part on how well the electret was initially manufactured.

The cost to recharge an electret is a fraction of the cost of new electrets. Recharged electrets provide economic benefits to the user, and an environmentally sound approach to business.

To have your electrets recharged, please fill out the order formand return with electrets and form of payment to RTCA®.

1. “An Electret Passive Environmental 222Rn Monitor Based on Ionization Measurement”, Kotrappa, P., Health Physics Vol. 54, No. 1 (January), pp. 47-56, 1988.